Cutter head,particularly for gear-cutting machine



Oct. 6, 1970 I o us 3,531,843

' CUTTER HEAD, PARTICULARLY FOR GEAR-CUTTING MACHINE Filed Dec. 6, 1968 2 Sheets-Sheet 1 Fig. 1

ERICH KOTTHAUS Inventor Attorneys Oct. 6, 1970 E. KOTTHAUS 3,531,843

CUTTER HEAD, PARTICULARLY FOR GEAR-CUTTING MACHINE Filed Dec. 6, 1968 2 Sheets-Sheet 2 ERICH KOTTHAUS, Inventor Attorneys United States Patent 3,531,843 CUTTER HEAD, PARTICULARLY FOR GEAR- CUTTING MACHINE Erich Kotthaus, Kloten, Switzerland, assiguor to Werkzeugmaschineufabrik Oerlikon Buhrle AG, Zurich,

Switzerland Filed Dec. 6, 1968, Ser. No. 781,775 Claims priority, application Switzerland, Jan. 8, 1968, 226/68 Int. Cl. B26d 1/12; B23c 1/00 U.S. Cl. 29-105 6 Claims ABSTRACT OF THE DISCLOSURE A cutter head for a gear-cutting machine and the like having a disc-shaped body with a seating surface at the rear disposed at right angles to the axis of the body. An elastically resilient hub in the interior of and connected to the body having a conical centering bore with the axis of the bore coinciding with the axis of the body. Radiallydisposed ribs extend in an axial direction over the entire width of the hub connect the hub to the body. The wall of the conical bore has recesses in the region of the ribs whereby the hub is more elastically resilient between the ribs than in the region of the ribs. The ribs are formed by a number of bores disposed in a circle concentric to the centering bore of the hub.

The invention relates to a cutter head, particularly for a gear-cutting machine having a disc-shaped body with a seating surface at the rear disposed at right-angles to the axis of the body, with an elastically resilient hub in the interior of and connected to the body and having a conical centering bore, the axis of which coincides with the axis of the body.

In the case of a known cutter head of this type, the outer side of the hub extending along the axis is separated from the body by an annular gap and only the front or rear end of the hub, viewed in the axial direction, is connected to the body by a web engaging on this end. It is indeed possible, by suitable dimensioning of the Web, to construct this latter to be so elastically resilient that the elevation of the stresses in the hub which occurs when the hub is pushed on to a mandrel of a thickness which is somewhat greater than the desired thickness, until its seating face bears against an abutment face on the mandrel, is transmitted to the body itself to a lesser degree than if the hub were solidly connected to the body. As a result of the unilateral attachment of the web on one end of the hub, the other end thereof is however not in immediate connection with the body and so has a reduced resistance to expansion in a radial direction than the end which is connected to the web. This asymmetry produces an uneven distribution along the hub of the pressure pressing the hub against the mandrel, and this may be the cause of an eccentric positioning of the body in relation to the mandrel.

The object of the present invention is to obviate this disadvantage. The cutter head according to the invention is characterised in that the hub is connected to the body of the cutter head by radially disposed ribs extending in an axial direction over the entire width of the hub, the wall of the conical bore having recesses in the zone of the ribs and the hub being more elastically resilient between the ribs than in the zone of the ribs.

By way of example, an embodiment of the cutter head according to the invention is described in detail hereinafter, with reference to the attached drawings, in which:

FIG. 1 is an axial cross-section through a face cutter head and the end of the arbor supporting it;

3,531,843 Patented Oct. 6, 1970 FIG. 2 is a partial rear view of the cutter head after removal of the arbor according to a second embodiment;

FIG. 3 is a sectional view of the cutter head shown in FIG. 2 and FIG. 4 is the same as FIG. 2 with the cutter head hub expanded.

According to FIG. 1, a work spindle 10 is mounted about an axis 11 in a spindle stock housing (not shown) of a gear-cutting machine. FIG. 1 shows only a part of the front end of this work spindle 10 which has a plane end face 12 disposed at right-angles to the axis 11. From this end face 12, a conically shaped pin-member 13 protrudes having a peripheral surface 14 equiaxial with the axis 11. Likewise equiaxial in the pinmember 13 is a threaded bore 15.

Mounted on the work spindle 10 is a cutter head 16 having a disc-shaped body 17, from which a series of cutters 18 project, in fact in the direction of the axis 11. They are usually disposed in a circle concentric with the axis 11, though they may however also be disposed along one or a plurality of spirals surrounding the axes. The end faces of the cutters, i.e. the faces which encounter the workpiece as the cutter head rotates, have inner and outer lateral edges 19 and 20 as well as front edges 21. In the case of many cutter heads, only the inner and front edges 19 and 21 form a cutting action, while in the case of others this action is performed by only the outer and the front edges 20, 21. There are also cutter heads in which the inner edge 19 and outer edge 20 cut alternately, while the front edge 21 of each cutter performs a cutting action. Then again, there are cutter heads on which only every second cutter 18 cuts, applying its front edge 21 and side edge 19 or 20. There are also various other arrangements of cutters 18.

The cutters 18 are adjustably anchored in the cutter head 16 in a manner which is not shown in the drawings.

The cutter head 16 is mounted on the spindle by a screw bolt 22. The bolt 22 passes through a central bore 23 in the disc 17 and is screwed into the threaded bore 15 of the work spindle. The bolt 22 has a head 24 having a hexagonal recess 25 for insertion of a key. The head 24 is located in the interior of the disc-shaped body 17.

The rear seating surface 26 of the cutter head 16 is pressed against the end face 12 of the work spindle 10 by the bolt 22, in order to secure the cutter head exactly in a plane extending at right-angles to the axis 11. The cutter head is fitted on to the conical surface 14 of the spindle pin 13 by means of a conical bore 27, the connection being by a press fit, when the cutter head 16 is flush against the face 12 of the spindle 10. The spindle 10 drives the cutter head 16 by means of a spline (not shown) disposed on the end face 12 of the spindle 10 and engaging in a groove (not shown) on the rear face 26 of the cutter head 16. In some cases, this spline may also ensure a definite angular position between the cutter head 16 and the spindle 10.

According to the invention, a number of bores 28 are disposed in the rear face 26, their axes 29 being in a circle concentric with the spindle axis 11. These bore axes 29 may be disposed either parallel with the spindle axis 11 or, as shown in FIG. 3, they may be inclined at an angle to the spindle axis 11. This angle corresponds to the angle enclosed by the generatrix of the conical face of the bore 27 and the spindle axis 11. This angle is for example 77'30".

The conical bore 27 discharges into a hollow space 30, the diameter of which is so selected that passages 31 are formed between the circularly-disposed bores 28 and the said hollow space 30. The conical bore 27, the circle of bores 28, the hollow space 30 and the passages 31 bound an elastically resilient hub 32, the axis of which coincides with the axis of the body, the hub being connected to the disc-shaped body 17 only by ribs 33. In the zone of these radially disposed ribs 33 are provided, in the wall of the conical bore 27 and extending over the entire width of the hub 32, recesses 34 which prevent the pin-member 13 of the work spindle bearing on the hub 32 in the zone of the ribs 33. These recesses may have a circularly cylindrical limitation. As can be seen particularly in FIG. 3, the ribs 33 which are substantially bound by the walls of the bores 28, extend in an axial direction over the entire width of the hub 32 which is more resilient between the ribs 33 than in the region of the ribs.

The device described functions in the following manner:

So long as the diameter of the conical bolt 13 of the work spindle 10 and of the conical bore 27 of the cutter head 16 are exactly matched and are at the same temperature, there is no difficulty in so securing the cutter head 16 on the work spindle 10 by means of the bolt 15 that the seating face 26 of the cutter head 16 bears flush on the end face 12 of the work spindle 10. However, if a cold cutter head has to be fitted on a spindle which has become heated by work, then the bores 28 and the recesses 34 make it possible for the conical bore in the hub 32 of the cutter head 16 to expand without considerable forces being necessary in order to bring the seating face 26 of the cutter head to bear on the end face 12 of the work spindle 10.

In the event of the pin-member 13 becoming expanded, e.g. by heating, the hub 32 may be elastically deformed in the region between the ribs 33. As can be seen from FIG. 4, the radius of the conical bore 27 has expanded by the amount D, so that, as can be seen from FIG. 4, the bores 28 deform without considerable stresses arising in the disc-shaped body 17 of the cutter head. In the case of a preferred embodiment, the maximum diameter of the conical pin-member 13 of the work spindle 10 is 130.11 mm. with a tolerance of 0 and +0.00% mm., while the maximum diameter of the conical bore 27 is likewise 130.11 mm. with an admissible tolerance of +0 and 0.008 mm., the cone being in both cases 1:4, i.e. the angle of inclination is, as already mentioned, 77'7, for with a length of the cone of 4 units, the difference in diameters represents 4 units I claim:

1. A cutter head for a gear-cutting machine and the like comprising a disc-shaped body having a seating surface at the rear disposed at right angles to the axis of said body, an elastically resilient hub in the interior of and connected to said body having a conical centering bore, the axis of said bore coinciding with the axis of said body, radially-disposed ribs (33) extending in an axial direction over the entire width of said hub (32) connecting said hub (32) to said body (17), the wall of said conical bore (27) having recesses (34) in the region of said ribs (33) whereby said hub (32) is more elastically resilient between said ribs (33) than in the region of said ribs (33).

2. A cutter head according to claim 1 wherein said ribs (33) are formed by a number of bores (28) disposed in a circle concentric to said bore (27) of said hub.

33. A cutter head according to claim 2 wherein both said centering bore (27) and said bores (28) which are disposed in a circle terminate in a hollow space (30) in the interior of said body (17).

4. A cutter head according to claim 3 wherein the axes of said bores which are disposed in a circle are inclined by the same angle in relation to the axis of said body as is the generatrix of said conical bore wall (27).

5. A cutter head according to claim 1 wherein said recesses (34) in the region of said ribs (33) extend over the full width of said hub (32).

6. A cutter head according to claim 5 wherein said recesses have a circularly cylindrical limitation.

References Cited UNITED STATES PATENTS 1,442,659 1/1923 Groene -11 2,212,406 8/1940 Rushak 29103 X 2,828,672 4/1958 McMullen 29105 X 2,983,166 5/1961 Davidson 29105 X 3,138,996 6/1964 Dammert et al. 29-l05 X FOREIGN PATENTS 1,023,654 1/1958 Germany. 143,759 1/1954 Sweden.

HARRISON L. HINSON, Primary Examiner US. Cl. X.R. 901l 

